Milo g



(No Model.)

M. G. KELLOGG. MULTIPLE SWITGHBOARD. No. 592,361 Patented Oct. 26, 1897.

rurrnn STATES MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG SYVITCIIBOARD AND SUPPLY COMPANY, OF SAME PLACE.

M ULTIPLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 592,351, dated October 26, 1897.

Application filed January 4,1890. Serial No. 335,859. (No model.)

To aZZ whont it may concern:

Be it known that I, MILO G. KELLOGG, of Chicago, in the county of Cook and State of Illinois,ten1porarily residing at Stuttgart, in the Empire of Germany, have invented cer' tain new and useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the following isafull, clear, concise, and eXact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a telephone-exchange system in which the lines are single circuit lines grounded at their outer ends; and it consists of apparatus for switching such lines of the exchange in the operation of the exchange system and a system of testing the lines to determine whether they are in use.

In the drawings illustrating my invention, Figures 1 and 1 represent sections of two multiple switchboards of the exchange to which the same lines are connected. Fig. 2 shows a diagram of the boards with the mainline apparatus and connections necessary to illustrate my invention. Fig. 2 is a detail view of one of the line-annunciators. Fig. 3 shows a diagram of an operators cord system to be used in connection with the boards. Fig. 4 shows an operators test system to be used at the boards.

In Fig. 2,A is a sectional View of the switchboard shown in Fig. 1, and A is a sectional View of the switchboard shown in Fig. 1, each as indicated by the line cl 6.

I place as many boards in the central office as are found necessary or desirable in order to properly operate the exchange. 011 each board is a spring-jack or other suitable switch for each line. Each switch has a contactspring which normally connects with an insulated contactpiece and is adapted to re ceive aloop-plu g and, when a plug is inserted, to disconnect the spring from the contactpiece and connect the two contact-pieces of the plug with the spring and said insulated contactpiece, respectively. The switch is also adapted to receive a single-contact switchplug and, when a plug is inserted, to disconnect the spring from the contact-piece and connect the spring with the contact-piece of the plug. In the construction of the switches as shown and as will hereinafter be described Iprefer to have a contact-point electrically connected with the contact piece and on which the spring normally bears, as there is less chance of poor connection when the spring bears on apoint than when it bears on a surface adapted to be brought into connection with the plug-contacts.

In Fig. 2, g 9 represent the springs of the different switches, h h the contact-points on which the springs normally bear, and j j the contact-pieces of the switches connected with the points it h. Z Z are the switch-holes, a b are the rubberstrips on which the metal parts of the switches are mounted, as shown, and through the fronts of which are the switchholes Z Z. The contact-piecesjj are so placed along one of the surfaces of the plug-holes as readily to form connection with one of the contact-pieces of the loop-plugs. The holes ZZare adapted to receive the switch-plugs shown in Fig. 3 and marked D D, and when a plug is insertedint-o a switch it raises the spring 9 from the contact-point h and the spring 9 and the contact-piece of the plug are in contact. These holes are also adapted to receive the lo0p-plug shown in Fig. 4, and when a plug is inserted into a hole it raises the spring of the switch from the contact-point h and the spring 9 and the contactpiece j of the switch are in contact with the two contact-pieces of the plug, respectively.

to and 0c are calling-annunciators, one for each of the lines shown. Each annunciator has a pair of contact-points normally (or when the annunciator does not indicate a call) in contact with each other, but which are separated by the annunciator while it indicates a call. The two contact-points of a pair are marked p and g, respectively. One of them, q, is a spring-contact, which is pressed by the annunciator-drop, when the drop falls, away from its corresponding contact-point p. The contact-point p is represented. as an angle piece, which. passes over the spring q and is in contact with the spring when the spring is not actuated by the annunciator-drop.

The ann unciator is shown in'detail in Fig. 2. The line runs to an insulated bolt 0 at the top of the annunciator-plate o, thence through the annunciator-coil to the plate, and

thence normally through spring g, which is in electrical contact with the plate, to the insulated angle-piece 1), against which spring q normally bears, and thence to earth.

Two lines areshown in the drawings, one marked line No. 1 and the other line No. 2. These llnes are ordinary single-circuit lines grounded at their outer ends and having at the subscribers stations any usual and appropriate subscribers station apparatus. Each line passes successively through the pairs of contacts of its switches on the several boards, passing in each case to the spring first. It then passes through its line-annunciator and the pair'of contact-points of the annunciator to the ground. The circuit of each line shown may thus be traced in Fig. 2. In the operators cord system shown in Fig. 3, D D are the switch plugs of a pair of cords, n n are the rubber insulations of the plugs, and m -m are their contact-pieces. These contact-pieces pass each to the bottom of its plug and are adapted to rest normally or when the plug is not in use on the metal piece 0, which then connects it with the ground. Weights, as is usual, or similar devices may be used to bring the contact-pieces of the plugs into contact with the piece 0 and secure a good connection. These plugs are adapted to be inserted into any of the switches at their board, and when a plug is inserted it operates the switch, as above described. The plugs should be inserted so that the contactpiece m is in contact with the spring g. The connect-ions of the lines might have been reversed, so that the lines pass first to the contact-piece j of each of their switches, and in that case the plugs should be inserted in such a position that their contact-pieces form connection with the pieces 3' of the switches. Y is the looping-in switch for the pair of cords shown. is the calling-key. O is a condenser, and l; is a clearing-out annunciator.

i is the operators telephone, and B is her calling generator or battery. are substantially as shown.

The two contact-pieces of the plugs are connected by flexible conductors to the two levers, respectively, of the looping-in switch.

One of the pairs of contact-bolts of the switch are connected together through the clearingout annunciator and the other pair are connected through the operators telephone. The

lever of the calling-key is connected to one of the cords, and the point of the keyis grounded through the calling generator or battery. The

condenser is placed in the circuit of the other cordof the pair.

those skilled in the art. apparent that when a line is switched by the insertion of a plug into its switch the line is disconnected from its normal ground at the central oiiice and is connected into a circuit with the pair of cords and that the condenser I of the pair of cords is in its circuit. Only apparent to those skilled in the art.

The circuits one pair of cords is shown, but the connection of such other pairs, with their accompanying apparatus as the operator may need, will be To each pair of cords, with its plugs, belong a loopingin switch, a condenser, a clearing-out annunciator, and a calling-key. One telephone and one calling-generator will answer for her system of cords. The plugs should be inserted into the switches of the line, so that the calling-key is connected to the circuit of the cords between the condenser, and the switch-plug inserted into the line whose bell it may be desired to ring. If desired, two calling-keys may be used for each pair of cords, one connected on each side of the condenser.

In the operators test system shown in Fig. 4, T is a loop test-plug, adapted to be inserted into any of the switches, and when inserted to operate them, as heretofore described. 13 is a test-battery, and S is a test receiving instrument. The battery and instrument are connected in a loop which terminates in the two contact-pieces of the plug. Each operator has one cord system and one test system, and they are conveniently mounted and arranged for her work.

The test receiving instrument and battery are so constructed and related to eachother that when they are looped into the circuit with any line and the circuit is not open at some pair of contact-points and has no condenser in its circuit the instrument will sound or respond, but when the circuit is open at any point or has a condenser in it the'instrument will not sound or respond.

The operation of the test system is as follows: WVhen an operator desires to test a line, she places her test-plug into the switch of the line, and by so doing disconnects the pieces 9 and j of the switch and connects them with the contact-pieces of the plug. If, then, the lineis not switched at any switch and its annunciator does not indicate a call, the instrument and battery are on a closed circuit with the line and the instrument will sound or respond, indicating that the line is free to be connected to. If, however, the line-annunciator indicates a call, (and the line is not switched,) the circuit is open at the. pair of IIO annunciator contact-points and the instru- 1 open at the pair of contacts 9 h of the switch Theoperation of the system in connection with the switchboards will be apparent to It will readily be i used for switching and the test receiving instrument will not sound. If, again, the line is switched at any board and the test-plug is inserted into a switch which is between the one used and the subscribers station, the test-- circuit is open at the condenser which is in circuit with the line and the instrument will not sound. WVhen a test of a line is made and the test receiving instrument sounds or responds, the operator therefore knows that neither the line is switched for use at any board nor its annunciator indicates a call and that she may connect the line with another. \Vhen she makes the test and the instrument does not sound, she knows that either the line is switched for use at some board or its annunciator indicates a call, and she will not connect it with another line. By this system of switching and testing a snbscribers line tests busy when it is switched and when his annunciator indicates a call. His line is reserved to himself as soon as he has sent in a call and will not be switched with another line before his operator has had time to answer his call, to his confusion and annoyance. In this system also there are only two contacts for each line on each board, instead of three or n1ore,as in other systems with groundeircuit lines, and there is only one wire leading in and one leading out from each switch, instead of three or more in other systems. There is also but one wire between any two boards for each line, instead of two or more, as in other systems.

I claim as my invention and desire to secure by Letters Patent- 1. In a telephone-exchange system, a telephone-line normally passing, successively, through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board and through a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with a loop test-plug in the two contact-pieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said loop-plug being adapted to be inserted into a switch of the line and when inserted to separate the said two contact-points of the switch and connect them with the two contact-pieces of the plug, substantially as set forth.

2. In a telephone-exchange system, a telephone-line grounded at its outer end and normally passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contactpoints normally closed but open while the annunciator indicates a call, and thence to ground, in combination with a loop test-plug in the two contact-pieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said loopplug being adapted to be inserted into a switch of the line and when inserted to separate the said two contact-points of the switch and connect them with the two contact-pieces of the plug, substantially as set forth.

3. In a telephone-exchange system, a telephone-line normally on closed circuit and passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with a loop test-plug in the two contact-pieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said loop-plug being adapted to be inserted into a switch of the line and when inserted to separate the said two contact-points of the switch and connect them with the two contact-pieces of the plug, substantially as set forth.

4. In a telephonaexchange system, a telephone-line normally on closed circuit and passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally in contact but open while the line is switched at their board and through a pair of annunciator contactpoints normally in contact but open while the annunciator indicates a call, in combina tion with a loop test-plug in the two contactpieces of which terminate the two sides of a loop which contains a test receiving instrument, said loop-plug being adapted to be inserted into a switch of the line and when inserted. to separate the said two contact-points of the switch and connect them with the two contact-pieces of the plug, and a test-battery in the test-circuit established on testing, sub stantially as set forth.

5. In a telephone-exchange system, a telephone-line grounded at its outer end and normally passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally in contact but open while the line is switched at their board, and through a pair of annunciator contact-points normally in contact but open while the annunciator indicates a call, in combination with a loop test-plug in the two contact-pieces of which terminate the two sides of a loop which contains a test receiving instrument, said loop-plug being adapted to be inserted into a switch of the line and when inserted to separate the said two contact-points of the switch and connect them withthe two contact-pieces of the plug, and a battery in the test-circuit established on testing, substantially as set forth.

6. In a telephone-exchange system, a telephone line normally passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with switching devices at each board to disconnect said pair of contact-points at the board and switch the line for conversation with a condenser in circuit when the line is switched but not otherwise, and a loop test-plug in the two contact-pieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said loop-plug being adapted to be inserted into a switch and when inserted to disconnect said two contact points of the switch and connect them with the two contactpieces of the plug, substantially as set forth.

7. In a telephone-exchange system, a telephone-line grounded at its outer end and normally passing, successively, through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contactpoints normally closed but open while the annunciator indicates a call, and thence to ground, in combination with switching devices at each board to disconnect said pair of switch contact-points at the board and switch the line for conversation with a condenser in circuit when the line is switched and only then ,"and a loop test-plug in the two contactpieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said plug being adapted to be inserted into a switch and when inserted to disconnect said two contact-points of the switch and connect'them with the two contact-pieces of the plug, substantially as set forth.

8. In a telephone-exchange system, a telephone-line normally on closed circuit and passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with switching devices at each board to disconnect said pair of switch contact-points at the board and switch the line for conversation with a condenser in circuit when the line is switched and only then and a loop test-plu g in the two contact-pieces of which terminate the two sides of a loop containing a test receiving instrument and battery, said loop-plug being adapted to be inserted into a switch and when inserted todisconnect said two contact-points of the switch and connect them with the two contact-pieces of' the plug, substantially as set forth. g 9. In a telephone-exchange system, a telephone-line grounded at its outer end and normally passing, successively, through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through a pair of annunciator contactpoints normally closed but open while the annunciator indicates a call, and thence to the ground, in combination with switching devices at each board to disconnect said pair of switch contact-points at the board and switch the line for conversation with a condenser in the circuit when the line is thus switched and only then, a loop test-plug in the two contactpieces of which terminate'the two sides of a loop which contains a test receiving instrument, said loop-plug being adapted to beinserted into a switch and when inserted to disconnect said two contact-points of the switch and connect them with the two contact-pieces of the plug, and a battery in the circuit established on testing,substantially as set forth.

10. In a telephone-exchange system, a telephone-line normally on closed circuit and passing successively through pairs of switch contact-points, one pair on each of several boards, each pair normally closed but open while the line is switched at their board, and through-a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with switching devices at each board to disconnect said pair of switch contact-points at the board and switch the line for conversation with a condenser in the circuit when the line is thus switched and only then, a test receiving instrument temporarily connected into the circuit, and a battery in the test-circuit established on testing, substantially as set forth.

11. In a telephone-exchange system, a telephone-line normally on closed circuit and having in its circuit pairs of switch contactpoints, one pair on each of the several boards, each pair normally closed but open while the line is switched for use and a pair of annunciator contact-points normally closed but open while the annunciatorindicates a call, in combination with switching devices at each board to disconnect said pair of contact-points at the board and switch the line for conversation with a condenser in the circuit when the line is thus switched and onlythen, and loop testplugs, one at each board, each plug having two contact-pieces in which terminate the two sides of a loop containing a test receiving instrument and battery and adapted to be inserted into the switch of the line at its board and when inserted to disconnect said pair of contact-points at the board which are normally in contact and connect them with the two contact-pieces of the plug, substantially as set forth.

12. In a telephone-exchange system, a telephone-line normally on closed circuit and having in its circuit pairs of switch contactpoints, one pair on each of the several boards, each pair normally closed but open while the line is switched for use, and a pair of annunciator contact-points normally closed but open while the annunciator indicates a call, in combination with switching devices at each board to disconnect said pair of switch contact-points at the board and switch the line for conversation with a condenser in the circuit when the line is switched and only then, loop test-plugs, one at each board, each plug having two contact-pieces in which terminate the two sides of a loop, containing a test receiving instrument and adapted to be inserted into the switch of the line at its board and when inserted to disconnect said pair of contact-points at the board which are normally in contact and connect them with the two IIO contactpieces of the plug, and battery in the test-circuit thereby established, substantially as set forth.

13. In a telephone-exchange system, multiple switchboards, telephone-lines, switches for said lines, one switch on each of the boards for each line, each switch having a pair of contact-points normally in contact, but open whileaswitch-plug is inserted, lineannunciators, one for each line, each annunciator having a pair of contact-points normally in contact but open while the annunciator indicates a call, each line passing successively through said pairs of contact-points of its switches on the boards and through the annunciator and pair of annunciator contactpoints, in combination with pairs of switchplugs at each board, the contact-pieces of each pair being connected by flexible conductors containing a condenser in their circuit, said plugs being adapted to be inserted into the switches at theirboards and when inserted to disconnect the pair of contact-points and 0011- neet the line contact-point of the switch with the plug contact-piece, and loop test-plugs, one at each board, each plug having two contact-pieces in which terminate the two sides of aloop containing a test receiving instrument and battery and adapted to be inserted into any switch at its board and when inserted to disconnect the two contact-points of the switch and connect them with the two contact-pieces of the plug, substantially as set forth.

14. In a telephone-exchange system, multiple switchboards, telephone-lines, each line being normally on closed circuit, switches for said lines, one switch on each of the boards for each line, each switch having a pair of contact-points normally in contact but open while a switch'plug is inserted, line-annunciators, one for each line, each annunciator having a pair of contact-points normally in contact but open while the annunciator indicates a call, each line passing successively through said pairs of contact-points of its switches on the boards and through the annunciator and pair of annunciator contact-points, in combination with pairs of switclrplugs at each board, the contact-pieces of each pair being connected by flexible conductors containingacondenser in their circuit, said plugs being adapted to be inserted into the switches at their boards and when inserted to disconnect the pair of contact-points and connect the line contact point of the switch with the plug contactpiece, and loop test-plugs, one at each board, each plug having two contact-pieces in which terminate the two sides of a loop containing a test receiving instrument and battery and adapted to be inserted into any switch at its board and when inserted to disconnect the two contact-points of the switch and connect them with the contact-pieces of the plug, substantially as set forth.

15. In a telephone-exchange system, multiple switchboards, telephone-lines, each line being normally on closed circuit, switches for said lines, one switch on each of the boards for each line, each switch having a pair of contact-points normallyin contact,but open while a switch-plug is inserted, line-annunciators, one for each line, each annunciator having a pair of contact-points normally in contact but open while the annunciator indicates a call, each line passing successively through said pairs of contact-points of its switches on the boards and through the annunciator and pair of annunciator contact-points, in combination with pairs of switch-plugs at each board, the contact-pieces of each pair being connected by flexible conductors containinga condenser in their circuit, said plugs being adapted to be inserted into the switches at their boards and when inserted to disconnect the pair of contact-points and connect the line contactpoint of the switch with the plug c0ntactpiece, and loop test-plugs, one at each board, each plug having two contact-pieces in which terminate the two sides of a loop containing a test receiving instrument and adapted to be inserted into any switch at its board and when inserted to disconnect the two contactpoints of the switch and connect them with the contact-pieces of the plug, and battery 95 in any test-circuit established on testing, substantially as set forth.

In witness whereof I hereunto subscribe my name this 13th day of December, 1889.

MILO G. KELLOGG.

Witnesses:

EMIL ABENHEIM, MARGARETHA RIEHL. 

